The ability of the organism to detect the presence of a target signal in a background of noise is much greater under binaural stimulus conditions in which there is an interaural difference in time of intensity between either the signal or the noise than under conditions in which there is no such difference. The brain mechanisms mediating this improvement in signal detectability are unknown and unexplored. The purpose of this project is to record the responses of neurons of the auditory system of the chinchilla, which has hearing similar to that of the human, while it is stimulated by the binaural sounds which produce the changes in signal detectability. The types of neurophysiological responses obtained will be related to the stimuli, to the neuroanatomy of the recording sites and to the theoretical models which have been proposed to account for the improvement on signal detectability.